The present invention relates to the removal of catalytic residues from hydrogenated unsaturated polymers utilizing specific amine compounds.
The catalytic hydrogenation of unsaturated polymers such as unsaturated rubbers is readily utilized in industrial processes. Many methods and compounds have been employed to deactivate and remove the catalysts which generally are organonickel, organoiron or organocobalt compounds. Usually these methods are not very efficient in the removal of substantially all of the catalysts, tend to be costly, involve complex methods or procedures and do not relate to the use of amine or glyoxime compounds.
Considering various prior art patents, U.S. Pat. No. 3,793,306, granted Feb. 19, 1974 to Farrar, relates to the addition of aqueous soluble phosphate salts in the presence of a thiuram polysulfide oxidant which reacts with a specific nickel catalyst. U.S. Pat. No. 3,793,307, granted Feb. 19, 1974 to DeVault is very similar to Farrar except that the oxidant is selected from the molecular oxygen or an oxygen-containing compound having an electro-chemical reaction potential of at least 0.25 volts at 25.degree. C. U.S. Pat. No. 3,780,137, granted to Hassell on Dec. 18, 1973, relates to a process of contacting a nickel catalyst residue with gaseous carbon monoxide to form nickel carbonyl and then volatilizing the nickel carbonyl from the polymer.
U.S. Pat. No. 3,780,138 to Hassell relates to a method for separating metal catalyst contaminates from organic polymers. However, it does not relate to the use of amine compounds which react with the catalytic residue to cause it to precipitate. Rather, this patent relates to the treatment of the metal contaminate with an oxidant and then treating the reaction product with an aqueous solution of citric acid which evidentally ties up or complexes the catalyst. U.S. Pat. No. 3,037,011 to Leibson et al does not relate to the removal of catalysts utilized in the hydrogenation of polymers, but rather to an anionic-type polymerization catalyst. This patent relates entirely to a method of finishing polymers of alpha-olefins in a manner to remove odor-forming materials. After the polymerization, it is necessary to solvate the catalyst components with quenching agents such as alcohols, ethers, and the like. Various leaching aids may be added during the solvation step. After the polymer is at least partially dried, an odorless diluent oxygen-containing azeotropic compound is added so that the odor-forming materials may be removed as a low boiling azeotrope with the azeotropic compound. Thus, the reference fails to suggest the utilization of applicant's amine compounds as well as any precipitation step.